salengro



P. A. ALENGR 2,899,934

POWER-DRIVEN TOOLS Aug. 1s, 1959 Filed Jan. 2, 1957 4 Shee{.s.-She^'3i'll ...m .veg-.1. l

Aug. 18, 1959 p, A SALENGRO ,n 2,899,934

POWER-DRIVEN TOOLS Filed Jan. 2, 1957 4 Sheets-Sheet 2 49 23 f-f 32a ,24/9..

Allg- 18, 1959 P. A. SALENGRO 2,899,934

POWER-DRIVEN TOOLS Filed Jan. 2, 1957 4 SheecS-She't 5 V 37 55s-ql z a52 525 fg.

MWM, Mm um 4 Sheets-Sheet 4 Filed Jan. 2, 1957 mah/.yf m 4110 a* @myarrangement ftnesupply'tubez l y y "'`I Fig, 4Y is" a view 'in elevationvvitl''a part iii *Cross`- ."secton, of av drilling'ftool constructed inaccordance with fthe invention. l f

United States Patent j nice 2,899,934 POWER-DRIVEN TOOLS YPaul A.Salengro, Antony, France Application January 2, 1957, Serial No. 632,189

Claims priority, application France January 19, 1956 12 Claims. (Cl.121-13) :'In his previous Patent No. 2,762,341, the applicant hasdescribed a power-driven tool, and in particular a pneumatic tool, inwhich the body of the tool or the motor element can slide in a kind ofcasing or guide which carries the operating handle. The damping of thevibrations of the motor element is ensured by fthe inter- -position,between the casing and the said element, of a variable volume of airwhichis connected without any substantial loss of pressure. to thesource of compressed air. In the case of a pneumatic tool, the airis-led to the mechanism of the motor element by a vcalibrated tube whichconnects this mechanism to the interior of the chamber containing thevolume of air yreferred to above, and various ,means are provided, on-lth'e one hand to ensure the fluid-tightness ofV the sliding faction ofvthis calibrated tube, irrespective of the amount This combinationespecially enables a variable rigidity 'to be obtained in operation, andin addition, it ensures ia better dampingor absorption of shocks whichmay be produced at the lend of the stroke of the motor element. i., Afurther improvement relatesvto a particular arrange- "'r'n'ent of l thecalibrated tube which connects the com- 'p'ressed 'air chamber to themechanism of the motor ,.element, .with a View to ensuring a variablecontrol of the admission of air tothe said mechanismV as a function of'the force applied by the operator on the handle. Further improvementswill be brought out from the 'description which follows below, referencebeing made to Athe accompanying drawings (which are given by 'way'ofexample lonly and not in any sense bly-Y way of limitation) and whichwill make` it quite clear how the invention may bel carried'int jeiect,the specialV features which are brought out, either inthe drawings or1inthe 'teigbeing understoodtofform a part of the said invention.

Fig.` 1 is a diagrammaticwview in longitudinal crosssection of apneumatic tool `such asa drilling hammer v Vcn'striicted inaccordancewith the invention.V

-' 'Figfl is a partial view similar Vto that kireceding and v .j-lrig. 2is a `an.grammes View iafingitudnai crossfseeri ef 'a second alternativerein erY censtfuction.

Fig. 3 is a partial viewiri cross-sectionshowing the Fig. 5 is a similarview of an alternative form of construction. f

In the form of construction shown in Fig. l, the pneumatic toolcomprises a guiding member or 4casing 1 which terminates at its upperpart in a handle. 2 which is provided in the usual mannerr with a valve3 controlled by a lever 4. The valve 3 enables the passage 5 tobevopened or closed, this passage connecting the compressed air intaketube 6 to the chamber '7 formed inside the handle 2.V The passage 5 isgiven fairly large dimensions in order to join the chamber 7 to thesource of compressed air without substantial loss of pressure.

A motor elementV 8 is mounted inside the vcasing 1L It can slide on twocylindrical bearing surfaces 9 and 10 ,of the said casing, co-operatingwith corresponding bearing surfaces 11 and 12 formedon the motorelement. Between these two pairs of bearing surfaces 9, 10 and 11, 12 isformed a space 13 which is connected to the atmosphere by means of ports14, into which space discharge the exhaust ports 15 of the motor element8.

The bearing surface 9 of the casing is preferably extended at 9a over acertain distance so as to constitute a supplementary Vmanual grip forthe tool.

At its lower part, the tool terminates in an end portion 16 (pick ordrill-bit) in the usual way; this end member is retained on the motorelement by means of a screwed sleeve 1'7 which is preferably providedwith a thickened portion 18 whichris intended to free the materialbetter in order to facilitate the penetration of the tool into thematerial.

A stud or small key 19 co-operating with a grooveZil formed in the motorelement may be provided in the body of the casing in order to preventthe motor element from ,rotating with respect to the casing. Thisarrangement also facilitates dismantling, for example by enabling one ofthe two elements (motor and casing) to be clamped in Va vice without theother being able to rotate.

The internal portion of the casing l on the other side of the bearingsurface 10 forms a chamber 21, in which vthe upper portion of the motorelement can move. This chamber is connected to the atmosphere by meansof ports 22 formed at various points. Y

Around the upper part of the motor element is wound a spring 23 which isheld between two rings 24 and 25. This spring can be compressed duringassembly, or it may be in its natural state between the two rings, whenno force is applied to the apparatus. The ring 24 can abut eitheragainst a flange 26 provided on the motor element, 'or against ashoulder 27 formed in the chamber 21,'de'- pending on the relativeposition occupied by the motor element and the casing. The ring 25 canabut in the same Way either against a flange Z8 onthe motor elemen oragainst a shoulder 29 on the casing.

In addition to this, abutments or stop members are provided on the onehand at 30 at the end of the bearing surface 10 for the flange 2'6, andon the other hand va't31 for the ring 24 in its movement towards thebottom of the casing. The'abutment 31 is preferably/ formed by theCollar of the member which constitutes the handle 2.

The motor mechanism of the toollisconnected tofthe chamber 7 by'Y meansof a calibrated tube 32 preferably heldin Vposition by a threaded ring33 which also the flange 28.

`The tube 32 passesthr'ough the wan 'which assente f lchamber 7 throughthein'edium of akdevice which enables the uidtightnes's of the slidingactionjof this tube to be obtained, whatever'postion the tube may takewith refspect to the casing. v This sealing device rmaybe of any ,Y

desired type, withr an Velastic or sliding mounting; .dei scribed 1n thepreviousrp'atent of the present'applicant r'- ferred to above. In thepresent'exam'ple, it comprises a sleeve 3.4"1'nou`nted with an easyfriction onthe tube-32 Patented Aug.Y 1s, 1959 :in place bya plug Y36which closes thechamber 7. -lI'he 'ange 34a is supported by a ring 37whichis-supported in its turn by a spherical bearing surface 37a on acircular seating 38, having the shape of a surface of revolution forexample a conical shape, provided in the parti- Ytion which separatesthe chamber 7 from the chamber .pose will be explained later.

The motor element comprises in the ordinary way-a cylindrical chamber40, in which is arranged to move the piston 41, the latter beingterminated by a nose 41a with which it strikes the pick 16.

'Ihe head of the motor element under the tube 32 comprises an annularvalve 42 which can open or close channels 43 leading directly to thecylinder 40, or channels 44 formed in the base 32a of the tube 32, andterminating in an annular space 45 which communicates by means of alongitudinal channel 46 with a port 47 located at the lower part of thecylinder 40. Above the port 47 grooves 48 are provided in the wall ofthe cylinder 40, these grooves communicating with each other and ,Wththe port 47, for example by means of the channel 4 The operation of thepneumatic tool which has just bee Ydescribed is as follows:

The motor element operates in the usual manner. Assuming that thevarious members are in the position shown in the drawing, the piston 41rests on the head of the pick and the portion of the cylinder 40 whichislocated above the piston communicates with the atmosphere through themedium of the ports 15 and 14. The valve 42 closes the channels 43. Y

If now the lever 4 is operated, compressed air passes into the chamber7, penetrates into the tube 32, passes through the channels 44 andarrives under the lower face of the piston 41 through the channel 46 andthel port 47. The piston 41 moves upwards, and when'it has uncovered theport 15, the compressed air which acted on its lower face passes out tothe atmosphere. v

During this time, the air enclosed in the upper part of the cylinder 4l)is subjected to compression by the piston 41 and lifts the valve 42. Thecompressed air then passes through the central opening of the annularvalve`42, and then through the channels 43 and pushes the pistondownwards; as it descends, the piston uncovers the port 15 which putsthe upper part of the cylinder l40 into communication with theatmosphere' and compresses the air located below the ports 15. The valve42 is again applied'to close the channels 43, and the cycle is repeatedas long as the lever 4 is actuated. e i i This operation will increasein rapidity as ay larger number of orifices 32b and 32e` of thecalibrated tube 32 are uncovered by the sleeve 34.

The grooves 4S are arranged so as to be closed by the piston when thelatter arrives at the end of its stroke, in order that the edge 41b ofthe lower face of the piston will no longer have to pass over saidgrooves if the piston continues to move downwards after having 'struckthe head of the pick. The grooves are especially intended to provide anYoptimum volume of air under the piston during the downward movement ofthis latter, in order to control the valve 42 which enables only asingle conduit 46 of small diameter to be employed, Vand in consequencethe thickness of` the walls of the motor element may be reduced whilesimplifying the machining of this ,spring 23.

, 4 element and enabling it conveniently to retain a shape of revolutionat the bearing surfaces 11 and 12; in addition, the body of the motorelement may be kept short and of small diameter, so that it is light.This assumes a special importance in the case of tools constructed inaccordance with the present invention, or in accordance with the patentreferredV to above, on the contrary to what takes place in the case ofmonobloc tools of usual type in which these problemsV of shape and bulkpractically do not arise. By providing a number of grooves, a betterrigidity of the cylinder is also ensured for a given volume of grooves,and the guiding of the piston is thereby improved. f In order to be ableto explain with greater clearness the operation of/the combined dampingdevice of the tool, it would appear desirable to study rst of all howthe sliding action of the motor element in the casing Vis effected,assuming that these two members are displaced without causing operationof the mechanism Vof the motor element.

It will be assumed that in the rst place, the valve 3 being closed, thevarious members areV in the positions shown in Fig. 1. The ring 24 isresting on the shoulder 27 and the spring 23 presses the ring 25 againstthe ange 28. In addition, the ring 24 is pressed against the ange 26,and a free space exists between the ring 25 and the stop member 29.

If pressure is applied to the handle 2, always Without opening the valve3, the motor element being for example held fixed, the casing will firstof all move freely downward until the stop member 29 comes into contactwith the ring 25. The casing will then act on the ring 25 and compressthe spring 23, the motor element remaining applied by the flange 26under the ring 24. This compression will continue until the stop member31 comes into contact with the ring 24.

When the pressure on the handle is released, the spring willprogressively expand until theV various members return again to theiroriginal positions. If at this moment a pull is applied to the handle,the casing will move the ring 24 to compress the spring 23 and willslide with re- Yspect to the motor element until the abutment 30 comesinto contact with the underside of the ange 26.V

The abutments 24-31 and 26-30 are provided in such manner as to preventany crushing of the turns of the spring 23 under the elect of extremeforces in tension or compression.

As soon as the compressed air is admitted to the apparatus, the pressureacting on the tube 32 pushes the motor element outV of the casing andcompresses the In addition, the motor element begins to vibratelongitudinally under the action of its mechanism.

The spring 23 damps these vibrations which would Votherwise be directlytransmitted to the casing by the apparatus which has come into abutmentwith the casing. In addition, the tube 32 has returned inside the sleeve34 and the motor mechanism, being only supplied through Athe orifice 32band perhaps through one of the orices 32C, is idling.

When the operator presses'down on the machine, the motor element movesupwards inside the casing, thus relieving the force acting on the spring23, which continues to contribute to the damping of the vibrations withthe air cushion of the ,chamber 7. The motor element thus oscillatesinside the casing about a mean position which will depend on V.the forceapplied by the operator on the handle.- The .harder-the operatorpresses, the closer this position Ybecomes to the bottom vof the casingand the more the upper extremity of the tube 32 will project out of thesleeve 34. l

At the same time, the number of the orices 32e which are uncoveredincreases, and with this, the power developed by the motor element.There is thus obtained a power consumption which varies with theforceapplied.

-r 0n the other hand, `it is necessary to lspace -apart the orifices321,` in order to obtain a sure and progressive control and a goode'icieney, taking account of the amplitude of lthe vibrations of themotor element.l The distance over which these orifices are formed isthus fairly great, and this is what produces the advantage of thevvariable rigidity of the-apparatus, conferred by the dead period due tothe space formed between the ring '2,5 and the shoulder A29, or betweenthe ring 24 and the shoulder 27',Y` depending on the relative positionsof the casing'and of the motor.

`This rigidity may even be Vnil if the dead space is chosen so as tobegreater than the amplitude of the vVibrations of the motor element,since `at this moment :the vibrations of the motor element do not applyany repercussion on the handle through the medium of the spring 23.``The rigidity increases in proportion as the force applied b'y theoperator becomes greater, and thus 'as'the mean positions of the ring 2Sand the abutment 29 become closer together, since then the reactions ofthe spring l23 on the handle become more powerful. When the ring 245 andthe stop member 29 are in permanent contact, the rate of ow of air fromthe motor mechanism is practically stable since the greater part of theorifices 32e are uncovered and, in view of the fact that the rigidityhas reachedits ,maximum value, the relative mean positions of the casingand the motor element vary very little with the applied force. l

If the operator presses too hard on the tool, the ring 24 lcomes intocontact with the stop member 31 and at that moment the operator feelsthe vibrations of the motor element and automatically relaxes hispressure on the tool.

If during the course of operation, for example in order to release apick which is jammed' in the material which is being broken up, theoperator is led to pull on the handle, the reverse operation to what hasbeen described takes'place, and the casing moves upwards along the motorelement to compress the spring, until the stop member'30 cornes kvintoccntact with the flange 26, this only taking place in the case of anexcessive pull being applied to the handle. Only the orifice 3217 isthen uncovered, and the consumption of air is small. At lthe end of thestroke, the orifice 32d passes out of the sleeve 34 and the compressedair escapes through the saidl orifice into 'the chamber 21 and fromthence to the atmosphere, stopping or considerably slowing-down theworking of the tool, and reducing in consequence the intensity of thevibrations` at the moment when the sliding members of the machine areapproaching their abutment members.

The alternative form shown in Fig. la difers'from the form of embodimentwhich has just been described by the provision of a supplementary spring49 interposed between the ring 24 and the stop member 29.

This spring acts alone at the beginning of the downward movement as longas the stop member 29 has not come into contact with the ring 25, andthe rigidity of the tool is low. When these members 29 and 25 are incontact, its action is added to that of the double-acting spring 23.When the operator pulls on the handle, only the spring 23 is in action,the supplementary spring 49 remaining at rest. For the remainder of thecycle, the operation is the same as that which has already beendescribed.

The base 32a of the tube 32 is given a slightly different shape in orderto co-operate with a valve 42, formed by a solid body sliding in afluid-tight manner inside its housing, this housing comprising twodifferent bores formed in the members 43a and 32a.

This base portion 32a still comprises however the channel or channels 44which lead to the channel 46 of the motor element. It defines, with themember 43a which is now provided with a central channel 43, an annularchamber 43b which communicates on the one 6 handV with the housing 42aof the valve through the intermediary of a channel 43e` and on the otherhand, with the bore of the' tube 32 by means of a channel 33e. TheYoperation of this valve arrangement isthe same as that which has ybeendescribed in connection with Fig. 1, the same pressures acting on thevalve in order to cause it to close either the channel 44 or the channel43. In the alternative form shown in Fig. 2, the double'- acting elastic-dampiug devicev is formed by two springs 50 and 51 arranged on eachside of a central ybearing surface 52 of the-motor element 8. y

The spring 50-is supported on the one Vhand against the upper face 52aof the bearing surface 52 and on the other hand against the base 53 ofVthe casing 1. This base also serves as a'stop member -for the end face54 of the 'motor element 8 in order to prevent Vcrushing o'f the spring.The lower springASl is supported against 'the lower face 52b of thebearing surface 52 and against aseating 55 formed in the casing l. Thetwo springs 50 and 51 are preferably compressed when assembled inposition in such manner that when the operatorA presses down on thehandle, the compression of one 4off-the springs increases, Whilst thatof the other decreases. v

The assembly of the calibrated tube 32 in the wall 53 Aof"V the chamber7 is also effected as with the preceding forms of embodiment, by meansof members which slide vone on the other by flat surfaces and lbyspherical and conical surfaces. In this case however, the sleeve 34comprises a flange 56 of cylindrical form and the ring 37 co-operateswith the said flange by means ofA a conical surface 57;. v In thiscasevals'o, Vfluid-tightness is ensured,

whateverV play there may exist between the various parts ofthe pneumatictool.

In -all the examples of construction described, the rigid'- -ityof thesprings is `chosen so that the operator ma'y press down or pull to areasonable extent on the handle without the machine coming intoabutment. In addition, the stiffness or strength of the springs ischosen so that the natural frequency of the elastic system is less thanthe frequency of percussion of the piston of the motor `mechanism on thepick.

All the preceding description mayl also be'applied to machines such aspneumatic drills or similar devices in which the drill or other endmember isV subjected not only to percussion but also to arotationalforce.

In these machines, the body of the motor element is subjected to areversing torque opposite to that which causes the drill to rotate. Inthe usual types of pneumatic drills, this torque is balanced by theoperator wit-hout any other medium than possibly a handle of rubber.

The device consisting of the key 19 and slot 20, which comprises theform of embodiment of Fig. 1, enables the application of the variousspecial features `described above to be made to drilling machineswithout any modication, provided that it is acceptable to transmitalmost the whole of the angular vibrations to the operator. Any otherdevice enabling the motor element and the casing to slide one withrespect to the other without rotation would also be suitable.

It is however preferable to provide elastic means to effect the dampingof the angular vibrations of the motor element with respect to thecasing. In the form of embodiment of Fig. 4, the stud or key 19 whichco-operates with the longitudinal slot 20 of the motor element l8 ismounted on the casing 1 through the ymedium of a ring 19a stuck to arubber ring 19b which is in turn stuck to the body of the casing 1. Thekey 19 passes of course through the wall of the casing 1 through anopening 20a of suitable dimensions; thus, the torsional vibrations ofthe motor element with respect to the casing are damped and the fatigueon the operator is considerably reduced. Y

In the alternative form shown in Fig. 5, the ring 19a is`mo`unted freelyon the' wall 1 of the casing and is'held in position by a stop ring 19e.A torsion spring 19d is fixed at one of its ends to the ring 19a and bythe other to the wall 1 of the casing. e

In addition, it is possible also to ensure the damping which forms thepresent problem by means of springs such as 23, 49, 50 and 51, of whichone extremity would be suitably connected to the motor element anditheother tothecasing.`

It will of course be understood that modiica'tions may be made to theforms of embodiment which have been described above, in particularV bythe substitution of equivalent technical means,- without'therebydeparting from the spirit or from the scope of the preserit invention.

Whatlclaimis:

l. A pneumatic drilling tool comprising in combination a hollow casingelement having opposing ends, one of said ends being open and grip meansprovided on the casing element adjacent the other end, apercussive motorelement slidably mounted in the casing element for limited movementthrough the open end, a partition meansextending across the casingelement Yabove'the open end and dening a chamber above the open end,means con- -necting the chamber with a source of compressed air, a tubemounted on one of the elements for conducting air from the chamber tothe motor element and Vdouble- -acting resilient means interposedbetweenl said motor element and said casing element for biasing saidmotor element to a mean position with respect to said` casing element. f2. The combination of claim 1 wherein said double acting resilient meansare adapted to be operative for a part of the relative displacement ofsaid elements.

3. The combination of claim 1, wherein said Vresilient means comprise adouble acting spring mounted between slidable rings arranged betweenstop members on said motor element and stop members on saidcasingelement.

4. The combination of claim 3, wherein said stop members on said motorelement are spaced apart by different distances than said stop memberson said casing.'

5. The combination of claim 3 wherein said resilient means furthercomprise a single acting spring inserted between one of said rings and astop member of one of said elements. Y Y

6. The combination of claim 1 wherein said tube is provided with anorice at one of its ends and comprises staggered orifices in its portionadjacent said end.

V`7. The combination of claim' l'wherein said tube slides through saidpartition means by means'of 'a sleeve,l said sleeve being mounted onsaid partition means by means of a sealing ring, said sleeve andring,fon one hand, and -said ring and partition means, on the other handbearing jon each other by Ymeans-of two`pairs of surfaces one of whichcomprises vtwo flat surfaces `and thefothera spherical surface'and asurface of revolution. Y l p '8. The combinationof claim 7 whereinsaidtube is provided with an orifice at one of its ends and with oriiices inthe portion adjacent said'nd, at least one of said last named on'cesbeing adapted vto bre/uncovered by said sleeve When'saidfmotor elementhas reached the maximum extend of `its stroke towards theopen end ofsaidcasing. 9. The combination of claim 7 wherein said'sleeve and .ring areforced against said partition-means by means of aspring- 77..' .f Y 10.The combination of claim 1 wherein said motor elementV comprises yaycylinder and a reciprocating piston adapted toV strike on a bit, saidcylinder comprising in its inner surface a .plurality ofV circular,Ygrooves communi- -eating with a channel connected to said tube, .saidgrooves being located in such a manner that they are covered by saidpiston when said piston strikes said-bit. Y11.v The combination of claim1 wherein means arefproyided for Vpreventing said motorrelement fromrotating with respect to said casing element and said last mentionedmeans are mounted resiliently on said element. l 12. The combination ofclaim 1 wherein means are provided for preventing said motor elementfrom rotating with respectto saidrcasing element and said last men#tionedmeans comprise` atleast apart of said resilient means.

- References Cited in the le of this patent 1 lf

